The sky wave with a frequency of 20 MHz is incidnet on D-region at an angle of `45^(@)`, then angle of refraction is

Options

A. `12.5^(@)`
B. `15^(@)`
C. `30^(@)`
D. `45^(@)`

Explanation

For D-region, `N=10^(9)m^(-3)`
Refractive index of a layer of atmosphere is
`mu=[1-(81.45N)/(v^(2))]^(1//2)=[1-(81.45xx10^(9))/((20xx10^(9))^(2))]^(1//2)` approx 1`
`mu=(sin i)/(sin r)approx1` or `sin r=sin i-=sin 45^(@)` or `r=45^(@)`